Molecular structure of amylopectin/amylose from Solanum lycocarpum starch after enzymatic hydrolysis

Abstract

The fruit of Solanum lycocarpum is a rich source of starch which remains unexploited despite its promising chemical and rheological properties. In this study, the molecular structures of amylopectin and amylose from S. lycocarpum starch were evaluated by HPAEC-PAD, being determined their chain length and degree of polymerization (DP). In addition, the starch was submitted to enzymatic hydrolysis using immobilized α-amylase (PANI-AMY) and glucoamylase (PANI-GLU). The enzymes immobilization onto polyaniline-glutaraldehyde derivatives was optimized through a Central Composite Rotatable Design (CCRD) and the hydrolysis products were characterized by Thin Layer Chromatography (TLC) and HPAEC-PAD. Results showed that amylopectin from S. lycocarpum starch had a maximal DP of 86, being observed a predominance of chains with type B1 (DP 13–24). On the other hand, the amylose is composed by short chain polymers, presenting DP of 57. Results from serial hydrolysis evidenced that the PANI-AMY reactor produced a set of malto-oligosaccharides, with predominance of pentoses (348.11 μg mL−1), while in the PANI-GLU reactor it was produced high levels of glucose. In addition, hydrolysis tests using high starch concentration (10% w/v) evidenced that the reactors can be efficiently used to hydrolyze starch at the similar concentration to that used in industrial processes, being able to efficiently produce starch liquefaction. Therefore, the results obtained in this work contribute to improve the information about the properties and potentialities of native and hydrolyzed starches from S. lycocarpum.